[galaxy-user] Q about 'Compute' tool

Hi, Can 'if' statements by used in 'Text manipulation' > 'Compute'? The reason is that i have a interval file of UCSC genes, i want to identify the TSS of each and make a new interval reflecting the TSS position for each gene. But because the TSS of a '-' stranded gene is actually the 'end' coord i want to be able to check the strand in the compute statement. Is this possible or is there an easier way to do this inside GALAXY? Thank you, Ian